I do not understand this word problem at all.

write an equation and solve.
A rectangle has a length of x+6 units and a width of x-3 units. what is the perimeter in terms of x?

P = 2L + 2W

P = 2(x+6) + 2(x - 3)

P = 2x + 12 + 2x - 6

P = 4x + 6

P - 6 = 4x

(p - 6)/4 = X